Kinetic Studies of Hantzsch Ester and Dihydrogen Donors Releasing Two Hydrogen Atoms in Acetonitrile.

In this work, kinetic studies on HEH 2 , 2-benzylmalononitrile, 2-benzyl-1 H -indene-1,3(2 H )-dione, 5-benzyl-2,2-dimethyl-1,3-dioxane-4,6-dione, 5-benzyl-1,3-dimethylpyrimidine-2,4,6(1 H ,3 H ,5 H )-trione, 2-(9 H -fluoren-9-yl)malononitrile, ethyl 2-cyano-2-(9 H -fluoren-9-yl)acetate, diethyl 2-(9 H -fluoren-9-yl)malonate, and the derivatives (28 XH 2 ) releasing two hydrogen atoms were carried out. The thermokinetic parameters Δ G ⧧ ° of 28 dihydrogen donors (XH 2 ) and the corresponding hydrogen atom acceptors (XH • ) in acetonitrile at 298 K were determined. The abilities of releasing two hydrogen atoms for these organic dihydrogen donors were researched using their thermokinetic parameters Δ G ⧧ °(XH 2 ), which can be used not only to compare the H-donating ability of different XH 2 qualitatively and quantitatively but also to predict the rates of HAT reactions. Predictions of rate constants for 12 HAT reactions using thermokinetic parameters were determined, and the reliabilities of the predicted results were also examined.